It is impolite to come into the office without ( )the doorA.knock B.knocking at C.to knock at D.knocking to

分类: 作业答案 • 2022-02-17 17:19:49

问题描述：

It is impolite to come into the office without ( )the door
A.knock B.knocking at C.to knock at D.knocking to

答

B,介词后+动名词